1. Coding the Universe
2. ∑n-definability without ∑n-induction;Chong;Trans. Amer. Math. Soc,1992
3. ∑n-definability without ∑n-induction,;Chong;Trans. Amer. Math. Soc.,1992
4. ∑2-induction and infinite injury priority arguments, Part II: Tame ∑2 sets and the jump operator;Chong;Ann. Pure Appl. Logic,1997